In many internal combustion engines it is desirable to filter the engine oil with two different types of filters, a full flow filter and a partial flow filter. The full flow filter is series connected to the oil circuit of the engine so that all of the oil circulating through the engine passes through the full flow filter, while the partial flow filter is connected to the oil circuit so that it receives a portion of the oil flowing through the engine. Typically, the partial flow filter is connected in parallel with a bypass device that carries a portion of the oil around the partial flow filter, and since the partial flow filter is not required to filter the full oil flow, it is usually designed to filter smaller particles from the oil as compared to a full flow filter.
At present, full flow and partial flow filters in an internal combustion engine are usually installed as separate filters which requires separate mounting systems and separate plumbing to invade the oil circuit of the engine in two different places. In some internal combustion engines it is difficult to provide sufficient space for two separate filters, and the hardware and labor needed to mount the second filter adds expense to the engine.
While present systems for providing full flow and partial flow filters are adequate, it would be preferred to use a single filter that would equal the performance of the two filter system. To achieve this goal, the present invention provides a filtering system in which two filters are detachably attached together and function as a single unit requiring only one mounting system on the engine. In a preferred mode, one of the filters would be a full flow filter, and the other would be a partial flow filter.
In accordance with the present invention, an oil filter is provided for attachment to an engine filter base having an engine outlet for transmitting oil under pressure to the filter and having an engine inlet for receiving oil from the filter. The filter includes a first can defining a first filter chamber having first and second ends. A first inlet receives oil into the first end of the first can, and a first outlet transmits oil from the first end of the first can. A second inlet receives oil into the second end of the first can, and a second outlet transmits oil from the second end of the first can. A second filter can defines a second filter chamber and includes a third inlet and a third outlet for receiving oil into and transmitting oil from the second can. First attachment apparatus is provided for detachably attaching the first end of the first can to the engine filter base and for sealably interconnecting the engine outlet with the first inlet and the engine inlet with the first outlet of the first can. A second attachment apparatus is provided for detachably attaching the second can to the second end of the first can and for sealably interconnecting the second outlet to the third inlet and the second inlet to the third outlet. First and second filter elements are disposed, respectively, in the first and second cans and a first flow directing device directs the oil flow in the first can from the first inlet to the second outlet and from the second inlet to the first outlet. This first flow directing apparatus is operable to direct at least some of the oil flow through the first filter element as the oil flows through the first can. A second flow directing means directs oil flow within the second can from the third inlet, at least partially through the second filter element and to the third outlet. In this construction, a single filter is constructed of two separable cans containing filter elements, either of which may be a full flow or a partial flow filter.
The oil filter of the present invention offers the performance and separation of two separate filters, a full flow filter and a partial flow filter, and yet it has the convenience and engine mounting simplicity of a single filter. The separability of the two filter cans allows a user to replace or clean the individual filter cans at different times and results in a more versatile overall filter. This separability also enables the convenient use of a permanent filter element in one can and a disposable filter element in the other can, if desired. For example, a truck engine will be operated in many different environments and the filter will be required to remove different quantities of particulates and water depending upon the environment. If few particulates are encountered in the oil, but the water content of the oil is high, the partial flow filter, which is usually designed to remove the water, may need changing more frequently. However, if the oil contains many large particles, but little water, the opposite result may occur, and the full flow filter must be changed more frequently. The separability of the two filter cans of the present invention allows either of the filters to be replaced or cleaned as needed.
The present oil filter also offers human engineering advantages. While the filter handles and fits the engine as a single filter, the owner can see that he has two filter cans, representing two filters to the owner, and he can easily take them apart. Since the filters are positioned in a side-by-side engaging relationship within the engine compartment, they will be exposed to the same environment and a visual inspection of the side-by-side filters will normally enable one to determine which filter was most recently installed. It is easy for the owner to visually inspect to insure that a mechanic has replaced the correct one of the filters. Thus, while the separability of the two filter cans provides functional advantages from a purely mechanical viewpoint, it also provides psychological or human engineering advantages.
While the invention in its preferred form has been described above as an oil filter for a truck, it will be understood that this filter can be used in a wide variety of fluid filtering applications.